Methane bubbles in the Arctic Ocean. Quantification, variability analysis and modelling of free and dissolved methane from the seafloor to the atmosphere
Intensive but heterogeneous and transient seepage of methane (CH4) bubbles from the seafloor exist west of Prins Karls Forland (PKF), offshore western Svalbard. The powerful greenhouse gas CH4, has 32 times higher warming potential than carbon dioxide (CO2) and if seepage of CH4 from the seafloor re...
Published in: | Limnology and Oceanography: Methods |
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Main Author: | |
Format: | Doctoral or Postdoctoral Thesis |
Language: | English |
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UiT Norges arktiske universitet
2018
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Subjects: | |
Online Access: | https://hdl.handle.net/10037/14485 |
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ftunivtroemsoe:oai:munin.uit.no:10037/14485 |
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openpolar |
institution |
Open Polar |
collection |
University of Tromsø: Munin Open Research Archive |
op_collection_id |
ftunivtroemsoe |
language |
English |
topic |
VDP::Mathematics and natural science: 400::Geosciences: 450::Oceanography: 452 VDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Oseanografi: 452 DOKTOR-008 |
spellingShingle |
VDP::Mathematics and natural science: 400::Geosciences: 450::Oceanography: 452 VDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Oseanografi: 452 DOKTOR-008 Jansson, Pär Methane bubbles in the Arctic Ocean. Quantification, variability analysis and modelling of free and dissolved methane from the seafloor to the atmosphere |
topic_facet |
VDP::Mathematics and natural science: 400::Geosciences: 450::Oceanography: 452 VDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Oseanografi: 452 DOKTOR-008 |
description |
Intensive but heterogeneous and transient seepage of methane (CH4) bubbles from the seafloor exist west of Prins Karls Forland (PKF), offshore western Svalbard. The powerful greenhouse gas CH4, has 32 times higher warming potential than carbon dioxide (CO2) and if seepage of CH4 from the seafloor reaches the atmosphere, it will contribute to the warming climate. Warming of the oceans may in turn, increase the release of CH4 to the water column, resulting in a positive feedback loop. Repeated surveys using an underwater acoustic remote sensing method for the quantification of benthic gas emissions suggest that the seepage west of PKF is modulated by transient opening of gas migration pathways in the sediments. We performed a three-fold repetition of a 64-station oceanographic survey grid with water sampling and simultaneous echosounding. The observations, together with numerical experiments using Lagrangian drifters, showed that that the fate of the emitted methane depends on both the seepage intensity and the temporal dispersion efficiency. We developed a process-based 1-dimensional model resolving free and dissolved gas of several species and several bubble sizes. The model includes user-chosen parametrizations of bubble shapes, rising speeds, and transfer velocities and was designed for easy integration into large-scale ocean circulation models. High-resolution measurements, using a towed, newly developed membrane-inlet laser spectrometer revealed intensive seepage and rapid diffusion near a seepage location 30 km west of Prins Karls Forland, offshore western Svalbard. A new 2-dimensional advection- diffusion model based on hydroacoustically mapped seepage intensity and the vertical distribution predicted by the 1-dimensional model reproduced the observed patterns of dissolved methane along the tow lines in the area. The research brings improved methods for quantification and upscaling of free gas flow rates, and modelling of free and dissolved gases in the water column. We anticipate that they will be used in future climate research, contributing to the understanding of the role of seafloor-emitted CH4 on ocean basin and global scales. |
format |
Doctoral or Postdoctoral Thesis |
author |
Jansson, Pär |
author_facet |
Jansson, Pär |
author_sort |
Jansson, Pär |
title |
Methane bubbles in the Arctic Ocean. Quantification, variability analysis and modelling of free and dissolved methane from the seafloor to the atmosphere |
title_short |
Methane bubbles in the Arctic Ocean. Quantification, variability analysis and modelling of free and dissolved methane from the seafloor to the atmosphere |
title_full |
Methane bubbles in the Arctic Ocean. Quantification, variability analysis and modelling of free and dissolved methane from the seafloor to the atmosphere |
title_fullStr |
Methane bubbles in the Arctic Ocean. Quantification, variability analysis and modelling of free and dissolved methane from the seafloor to the atmosphere |
title_full_unstemmed |
Methane bubbles in the Arctic Ocean. Quantification, variability analysis and modelling of free and dissolved methane from the seafloor to the atmosphere |
title_sort |
methane bubbles in the arctic ocean. quantification, variability analysis and modelling of free and dissolved methane from the seafloor to the atmosphere |
publisher |
UiT Norges arktiske universitet |
publishDate |
2018 |
url |
https://hdl.handle.net/10037/14485 |
long_lat |
ENVELOPE(11.175,11.175,78.543,78.543) |
geographic |
Arctic Arctic Ocean Prins Karls Forland Svalbard |
geographic_facet |
Arctic Arctic Ocean Prins Karls Forland Svalbard |
genre |
Arctic Arctic Ocean Prins Karls Forland Svalbard |
genre_facet |
Arctic Arctic Ocean Prins Karls Forland Svalbard |
op_relation |
Paper I: Veloso-Alarcón, M.E., Jansson, P., De Batist, M., Minshull, T.A., Westbrook, G.K., Pälike, H. … Greinert, J. Variability of acoustically evidenced methane bubble emissions offshore western Svalbard. (Submitted manuscript). Paper II: Silyakova, A., Jansson, P., Serov, P., Ferré, B., Pavlov, A.K., Hattermann, T. … Niemann, H. Physical controls of dynamics of methane venting from a shallow seep area west of Svalbard. (Submitted manuscript). Paper III: Jansson, P., Ferré, B., Silyakova, A., Dølven, K.O. & Omstedt, A. A new numerical model for understanding free and dissolved gas progression towards the atmosphere in aquatic methane seepage systems. (Submitted manuscript). Published version in Limnology and Oceanography: Methods , is available at https://doi.org/10.1002/lom3.10307. Paper IV: Triest, J., Jansson, P., Grilli, R., Ferré, B., Silyakova, A., Mienert, J. & Chappellaz, J. Insights from underwater high resolution dissolved methane sensing over a known methane seepage site west of Svalbard. (Submitted manuscript). 978-82-8236-320-4 (trykt) og 978-82-8236-321-1 (pdf) https://hdl.handle.net/10037/14485 |
op_rights |
openAccess Copyright 2018 The Author(s) |
container_title |
Limnology and Oceanography: Methods |
container_volume |
17 |
container_issue |
3 |
container_start_page |
223 |
op_container_end_page |
239 |
_version_ |
1766348250336460800 |
spelling |
ftunivtroemsoe:oai:munin.uit.no:10037/14485 2023-05-15T15:18:01+02:00 Methane bubbles in the Arctic Ocean. Quantification, variability analysis and modelling of free and dissolved methane from the seafloor to the atmosphere Jansson, Pär 2018-11-09 https://hdl.handle.net/10037/14485 eng eng UiT Norges arktiske universitet UiT The Arctic University of Norway Paper I: Veloso-Alarcón, M.E., Jansson, P., De Batist, M., Minshull, T.A., Westbrook, G.K., Pälike, H. … Greinert, J. Variability of acoustically evidenced methane bubble emissions offshore western Svalbard. (Submitted manuscript). Paper II: Silyakova, A., Jansson, P., Serov, P., Ferré, B., Pavlov, A.K., Hattermann, T. … Niemann, H. Physical controls of dynamics of methane venting from a shallow seep area west of Svalbard. (Submitted manuscript). Paper III: Jansson, P., Ferré, B., Silyakova, A., Dølven, K.O. & Omstedt, A. A new numerical model for understanding free and dissolved gas progression towards the atmosphere in aquatic methane seepage systems. (Submitted manuscript). Published version in Limnology and Oceanography: Methods , is available at https://doi.org/10.1002/lom3.10307. Paper IV: Triest, J., Jansson, P., Grilli, R., Ferré, B., Silyakova, A., Mienert, J. & Chappellaz, J. Insights from underwater high resolution dissolved methane sensing over a known methane seepage site west of Svalbard. (Submitted manuscript). 978-82-8236-320-4 (trykt) og 978-82-8236-321-1 (pdf) https://hdl.handle.net/10037/14485 openAccess Copyright 2018 The Author(s) VDP::Mathematics and natural science: 400::Geosciences: 450::Oceanography: 452 VDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Oseanografi: 452 DOKTOR-008 Doctoral thesis Doktorgradsavhandling 2018 ftunivtroemsoe 2021-06-25T17:56:12Z Intensive but heterogeneous and transient seepage of methane (CH4) bubbles from the seafloor exist west of Prins Karls Forland (PKF), offshore western Svalbard. The powerful greenhouse gas CH4, has 32 times higher warming potential than carbon dioxide (CO2) and if seepage of CH4 from the seafloor reaches the atmosphere, it will contribute to the warming climate. Warming of the oceans may in turn, increase the release of CH4 to the water column, resulting in a positive feedback loop. Repeated surveys using an underwater acoustic remote sensing method for the quantification of benthic gas emissions suggest that the seepage west of PKF is modulated by transient opening of gas migration pathways in the sediments. We performed a three-fold repetition of a 64-station oceanographic survey grid with water sampling and simultaneous echosounding. The observations, together with numerical experiments using Lagrangian drifters, showed that that the fate of the emitted methane depends on both the seepage intensity and the temporal dispersion efficiency. We developed a process-based 1-dimensional model resolving free and dissolved gas of several species and several bubble sizes. The model includes user-chosen parametrizations of bubble shapes, rising speeds, and transfer velocities and was designed for easy integration into large-scale ocean circulation models. High-resolution measurements, using a towed, newly developed membrane-inlet laser spectrometer revealed intensive seepage and rapid diffusion near a seepage location 30 km west of Prins Karls Forland, offshore western Svalbard. A new 2-dimensional advection- diffusion model based on hydroacoustically mapped seepage intensity and the vertical distribution predicted by the 1-dimensional model reproduced the observed patterns of dissolved methane along the tow lines in the area. The research brings improved methods for quantification and upscaling of free gas flow rates, and modelling of free and dissolved gases in the water column. We anticipate that they will be used in future climate research, contributing to the understanding of the role of seafloor-emitted CH4 on ocean basin and global scales. Doctoral or Postdoctoral Thesis Arctic Arctic Ocean Prins Karls Forland Svalbard University of Tromsø: Munin Open Research Archive Arctic Arctic Ocean Prins Karls Forland ENVELOPE(11.175,11.175,78.543,78.543) Svalbard Limnology and Oceanography: Methods 17 3 223 239 |